To survive and reproduce, animals acting in their natural environments must engage in a variety of behaviors such as procuring food, escaping predators, and seeking shelter or sexual partners. Because environmental constraints determine the most suitable times and places to perform specific behaviors and because many behaviors cannot be performed simultaneously, it is essential for animals to appropriately prioritize and organize when and where to engage in a particular behavior. As a result, the organization of behavior in a freely acting animal represents an adaptation to the environment This organization depends on the integrative activities of the central nervous system and reflects the functions and interactions of a diverse array of physiological and behavioral systems such as those regulating energy balance, thermal status, osmotic/volume status, sleep, reproduction, defense, and environmental entrainment. The ability to monitor and characterize the organization of behavior in a freely acting animal thus has the potential to provide a sensitive assay for examining the functions and interactions of numerous physiological and behavioral systems.
Substantial limitations currently exist in our ability to apply recent biotechnological advances to analyze neural substrates of complex mammalian behavior. In contrast to the rapid pace of innovation seen in the fields of mammalian genomics, medicinal chemistry and information technology, less progress has been made in the development of behavioral assessment techniques for mice or other mammals. Such procedures are vital for exploring the impact of genes, drugs and environment on brain functions relevant to common neuropsychiatric conditions such as schizophrenia, depression, and anxiety. Standard approaches, for example involving repeated removal of mice from their home cages for a battery of behavioral tests, are problematic because: 1) they are time-consuming and labor-intensive, 2) the order of test administration can skew the resulting data, 3) removal of mice from the home cage produces stress that confounds interpretation of behavioral data, and 4) data are frequently misinterpreted due to a failure to consider behavioral domains that are not the main focus of study (e.g.: impact of anxiety on tests of learning).